Biology subjects

Mankotia, S.

Publications and source records attributed to Mankotia, S..

4 recordsLinked to original sources

bioRxiv2026

HY5 orchestrates the transcriptional network controlling coumarin-mediated iron acquisition under elevated pH conditions

Iron (Fe) bioavailability is strongly limited in alkaline soils, where reduced Fe solubility severely restricts plant growth and productivity. To overcome this, Arabidopsis thaliana promotes Fe acquisition by secreting Fe-mobilizing coumarins, however, the transcriptional mechanisms coordinating this response is not clearly understood. Here we identify the ELONGATED HYPOCOTYL 5 (HY5), a bZIP transcription factor as a master regulator of coumarin mediated Fe acquisition under alkaline conditions. HY5 positively regulates genes required for coumarin biosynthesis, activation, secretion, and transcriptional control, and loss of HY5 markedly reduces their expression during high-pH-induced Fe deficiency. Chromatin immunoprecipitation analyses revealed that HY5 directly associates with the promoters of these genes, thereby establishing a transcriptional regulatory network that coordinates coumarin biosynthesis. Consistent with this regulatory function, hy5 mutants exhibit reduced coumarin accumulation, impaired root growth, chlorosis, and decreased Fe accumulation under alkaline conditions. Comparable phenotypes in coumarin-hy5 double mutants, together with the restoration of growth by exogenous fraxetin, demonstrate that HY5 functions upstream of coumarin-mediated Fe mobilization. Collectively, our findings identify HY5 as a molecular hub that integrates environmental pH signals with coumarin biosynthesis to promote adaptive Fe acquisition under alkaline conditions, providing a framework for improving crop performance on calcareous soils.

plant biology↗

bioRxiv2025

Blue Light Promotes Root Iron Acquisition via a Shoot CRY-HY5 Signaling Module in Arabidopsis.

O_LIIron (Fe) is an essential element for almost all living organisms and its deficiency severely impacts crop productivity and human health. While the mechanisms underlying iron uptake and accumulation are well studied, the role of light in modulating iron homeostasis remains poorly understood. In this study, we report that blue light enhances iron accumulation thereby positively regulating iron homeostasis in Arabidopsis thaliana. C_LIO_LIUnder iron-deficient conditions, root elongation is specifically promoted by blue light, not red light. We further revealed that, light perceived by shoots is required for optimum iron accumulation and for iron deficiency induced increase in root length. C_LIO_LIThe transcription factor HY5 (Elongated Hypocotyl 5), mediates these blue light-driven responses. The hy5 mutant showed reduced root elongation under -Fe conditions as well as iron accumulation under blue light as compared to wild-type plants. C_LIO_LIFurther we report that CRY1 and CRY2 are the photoreceptor that acts as a connecting link between blue light and HY5 to regulate iron uptake in Arabidopsis. C_LIO_LITaken together, our work reveals new regulatory mechanism and offers potential insights into optimizing light conditions to enhance iron accumulation and improve the nutritional quality of crops. C_LI

plant biology↗

bioRxiv2024

ELONGATED HYPOCOTYL 5 (HY5) and POPEYE (PYE) Regulate Intercellular Iron Transport in Plants.

Plants maintain iron (Fe) homeostasis under varying environmental conditions by balancing processes such as Fe uptake, transport, and storage. In Arabidopsis, POPEYE (PYE), a basic helix-loop-helix (bHLH) transcription factor (TF), has been shown to play a crucial role in regulating this balance. In recent years, the mechanisms regulating Fe uptake have been well established but the upstream transcriptional regulators of Fe transport and storage are still poorly understood. In this study, we report that ELONGATED HYPOCOTYL5 (HY5), a basic leucine zipper (bZIP) TF which has recently been shown to play a crucial role in Fe homeostasis, interacts with PYE. Molecular, genetic and biochemical approaches revealed that PYE and HY5 have overlapping as well as some distinct roles in regulation of Fe deficiency response. We found that HY5 and PYE both act as a repressor of Fe transport genes such as YSL3, FRD3 NPF5.9, YSL2, NAS4, and OPT3. HY5 was found to directly bind on the promoter of these genes and regulate intercellular Fe transport. Further analysis revealed that HY5 and PYE directly interact at the same region on PYE and NAS4 promoter. Overall, this study revealed that HY5 regulates Fe homeostasis by physically interacting with PYE as well as independently.

plant biology↗

bioRxiv2022

Elongated Hypocotyl 5 (HY5) regulates BRUTUS (BTS) to maintain Iron homeostasis in Arabidopsis thaliana.

Iron (Fe) is an essential micronutrient for both plants and animals. Fe limitation significantly reduces crop yield and therefore has adverse impacts on human nutrition. Owing to limited bioavailability of Fe, plants have adapted different strategies that regulate Fe uptake and homeostasis. Particularly, modifications of root growth traits are a key for the survival of plants on Fe-deficient soils. Understanding the molecular basis for these root growth responses will have critical implications for plant breeding. Fe uptake is regulated by a cascade of basic helix-loop-helix (bHLH) transcription factors. In our study, we show that HY5 (Elongated Hypocotyl 5), a member of the basic leucine zipper (bZIP) family of transcription factors plays an important role in the Fe deficiency signalling pathway in Arabidopsis thaliana. The hy5 mutant plants failed to mount an optimum Fe deficiency response and showed severe root growth defects under Fe limitation that could be partially reverted by complementation of hy5 mutant. qRT-PCR analysis revealed that the induction of the genes involved in Fe uptake pathway [FER-like iron deficiency-induced transcription factor (FIT), Ferric Reduction Oxidase 2 (FRO2) and Iron-Regulated Transporter1 (IRT1)] is significantly reduced in the hy5 mutants as compared to the wild-type plants under Fe deficiency. Moreover, we also found that HY5 function is critical for activating the expression of coumarin biosynthesis genes (F6H1, S8H, PDR9 and BGLU42) under Fe deficiency. Interestingly, our results showed that HY5 acts as a negative regulator of BRUTUS (BTS) which is known to negatively regulate Fe deficiency response. Chromatin Immunoprecipitation followed by qPCR revealed direct binding of HY5 to the promoter of BTS. Altogether, our results showed that HY5 plays an important role in regulation of Fe deficiency responses in Arabidopsis.

plant biology↗